Module Title: Accidents and Catastrophes
Learning Outcomes Critically evaluate characteristics of technological accidents and catastrophes, and methods of their investigation. Numerically estimate the impact of technological accidents and catastrophes. Appraise methods of decreasing risks of technological accidents. Critically analyze case studies, interpret lessons derived and their applications nationally and internationally. Report:
A bulk petrol storage facility is situated in an external tank farm. It is estimated that overfilling the vessel during offloading operations could occur once every five years. In order to prevent the hazardous liquid release from the tank vents, prior to any fuel delivery the tanks are manually dipped and the level recorded. Operators monitor the fill operations and intervene on detecting a high level by initiating a manual shutdown. At a pre-defined level of product an alarm will sound alerting the operators who again will intervene by initiating a manual shutdown. There is also an automatic ultimate high level device which automatically shuts down the fuel supply to the tank in the vent the operators have failed to take action. There are 50 fuel transfers into the tank per year. A risk tolerance criterion of 10-6 has been set as applying for all risks environmental, financial and safety.
a) Calculate the probability of a loss of product containment
b) Calculate the likelihood of the incident resulting in a vapour cloud explosion and fatality.
c) Illustrate your conclusions by drawing an fault tree
d) Comment on the level of risk against the risk tolerance criteria
e) Discuss the role that human error may play in the occurrence of a major incident, refer to the theoretical models of ‘human error’ and comment on the applicability of ‘Rasmussen’s SRK Taxonomy and Hale and Glendon’s ‘Behaviour in the Face of Danger Model’
f) What barriers/measures would you introduce to increase the level of safety and decrease the level of risk?
The following data is applicable: –
Probability of Ignition of fuel
Probability of personnel being in the affected area
Probability of fatality
Manual Fuel Check (PFD)
Level Gauges (PFD Hardware) Actions of Operator on sounding of alarm
Operation of High level alarm and automatic shut down
A written report to be word processed, a format should be adopted, which will include a title sheet, contents page and references. The report must not exceed 2,750 words Marking Scheme:
This assessment carries 40% of the weighting for this module. You must pass this element with 50% or above. Marks for the report will be allocated in the following manner.
Argument and structure
10% Assessment Feedback
Written feedback will be provided no later than 20th August 2015